當(dāng)我的 ajax 請(qǐng)求正在執(zhí)行時(shí)（對(duì)于 post 方法），我試圖通過(guò) PHP 連接到我的數(shù)據(jù)庫(kù)，但是如果無(wú)法連接，我想向我的用戶顯示一條錯(cuò)誤消息。我可以在連接時(shí)顯示成功消息，但我想知道是否有辦法手動(dòng)拋出 catch 塊，以便我知道我的代碼正在運(yùn)行，如果用戶無(wú)法連接到，則會(huì)向用戶顯示一條消息數(shù)據(jù)庫(kù)（目前使用 console.log 進(jìn)行測(cè)試）。JS$.ajax({  type: "post",  url: "test.php",  dataType: "json",  error: function(data) {    console.log(data.status);    console.log("Not Successful Test");    if (data.status == "connectionError") {      console.log("Didn't connect to database");    } else {      console.log("Other");    }  },  success: function(data) {    console.log(data.status);    console.log("Successful Test");    if (data.status == "success") {      console.log("Connected to Database");    } else {      console.log("Other");    }  }});測(cè)試.phptry {    require_once("dbConn.php");    $dbConn = getConnection();    $response_array["status"] = "success";} catch (Exception $e) {    $response_array["status"] = "connectionError"; // Want to display this response in JS code}header("Content-type: application/json");echo json_encode($response_array);dbConn.phpfunction getConnection(){    try {        $conn = new PDO(            "localhost=localhost;dbname=dbname",            "username",            "password"        );        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);        return $conn;    } catch (Exception $e) {        throw new Exception("Connection error " . $e->getMessage(), 0, $e);    }}解決方案 test.phptry {    require_once("dbConn.php");    $dbConn = getConnection();    $response_array["status"] = "success";} catch (Exception $e) {    // Added http response code then die() with message    http_response_code(503);    die("<b>Server Error.</b><br/> This service is currently unavailable. Please try again at a later time.");}header("Content-type: application/json");echo json_encode($response_array);